The present invention relates to an electrically heatable glazing panel.
In the case of heatable glazing panels comprising an electrically conductive coating layer and being of substantially regular shape, for example rectangular shape, electrical current is brought to a conductive coating layer through, for example, metallic bus bars, which are substantially parallel one to another. In this particular case the distance between the bus bars along their whole length remains substantially the same. The electrical resistance of the current path along the length of the bus bars is therefore substantially the same. When submitting such glazing panels to a given voltage, the amount of heat generated will be substantially uniform throughout the whole surface of the glazing panel covered with the conductive coating layer.
In the case of heatable glazing panels of substantially irregular shape, for example glazing panels with application in the automotive, railway or aeronautical field, bus bars may diverge at at least one portion along their length. The distance between the bus bars therefore varies and consequently the electrical resistance of the current path also varies. Therefore, when submitting such glazing panels to a given voltage, the amount of heat generated will vary along the length of the bus bars, thereby creating the risk of local areas of overheating which may damage or destroy the conductive coating layer. Furthermore, when such heatable glazing panels are used for de-misting or de-icing purposes, certain areas may de-mist or de-ice more rapidly than others. This may create problems of visibility for an observer looking through such a glazing panel.